In axial compressors, such as those used as a component in gas turbines, it is known to inject a fluid, such as water, into a gas passage, in which compression takes place, in order to influence a thermodynamic process being carried out. With such injection, consideration should be given to constructional characteristic features and geometric relationships in the axial compressor if extensive and costly modifications and adjustments in the structure of the axial compressor are to be avoided.
A compressor, in which for cooling the rotor shaft cooling air is blown through discharge openings in the blade tips of stator blades against the rotor shaft, is known from printed publication EP 0 984 138. Such a configuration may not be suitable for injecting a fluid into the gas flow, and can involve a special design of the stator blades.
In U.S. Pat. No. 6,644,935, it is proposed to inject a fluid into the gas flow for addressing efficiency in an axial compressor. To this end, radially oriented nozzles are accommodated directly in a bore in a casing of the compressor. Such a direct arrangement, with access from the outside, in a casing wall is possible in the case of compressors of which the casing structure is particularly simple. If, on the other hand, bleed air chambers and corresponding bleed air flanges are provided in the compressor, such a nozzle arrangement cannot be readily realized. Furthermore, sealing issues can occur, and also mechanical and thermal strength can be an issue.
U.S. Pat. No. 7,033,135 proposes to inject a fluid into the gas flow of a turbomachine through openings arranged in a distributed manner in a radial direction on a trailing edge of a stator blade. For connecting the stator blade to a fluid feed, the casing is expensively machined on the inside. Furthermore, the injecting of fluid in the flow direction is not particularly advantageous for mixing of gas and fluid mist.